Implement VFS superblock operations for FTRFS: - ftrfs_fill_super(): read and validate on-disk superblock (magic, CRC32), allocate ftrfs_sb_info, read root inode, initialize in-memory free block bitmap - ftrfs_put_super(): release bitmap and buffer heads on unmount - ftrfs_statfs(): report filesystem statistics - ftrfs_write_inode(): persist inode to disk via namei.c - ftrfs_init_fs_context() / ftrfs_get_tree(): kernel 5.15+ mount API - ftrfs_free_inode(): kernel 5.9+ inode freeing API Module init/exit registers ftrfs as a filesystem type and allocates a dedicated slab cache for ftrfs_inode_info objects. Signed-off-by: Aurelien DESBRIERES --- fs/ftrfs/super.c | 274 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 274 insertions(+) create mode 100644 fs/ftrfs/super.c diff --git a/fs/ftrfs/super.c b/fs/ftrfs/super.c new file mode 100644 index 000000000..8acc62921 --- /dev/null +++ b/fs/ftrfs/super.c @@ -0,0 +1,274 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * FTRFS — Superblock operations + * Author: roastercode - Aurelien DESBRIERES + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include "ftrfs.h" + +/* Inode cache (slab allocator) */ +static struct kmem_cache *ftrfs_inode_cachep; + +/* + * alloc_inode — allocate a new inode with ftrfs_inode_info embedded + */ +static struct inode *ftrfs_alloc_inode(struct super_block *sb) +{ + struct ftrfs_inode_info *fi; + + fi = kmem_cache_alloc(ftrfs_inode_cachep, GFP_KERNEL); + if (!fi) + return NULL; + + memset(fi->i_direct, 0, sizeof(fi->i_direct)); + fi->i_indirect = 0; + fi->i_dindirect = 0; + fi->i_flags = 0; + + return &fi->vfs_inode; +} + +/* + * free_inode — return inode to slab cache (kernel 5.9+ uses free_inode) + */ +static void ftrfs_free_inode(struct inode *inode) +{ + kmem_cache_free(ftrfs_inode_cachep, FTRFS_I(inode)); +} + +/* + * statfs — filesystem statistics + */ +static int ftrfs_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + struct super_block *sb = dentry->d_sb; + struct ftrfs_sb_info *sbi = FTRFS_SB(sb); + + buf->f_type = FTRFS_MAGIC; + buf->f_bsize = sb->s_blocksize; + buf->f_blocks = le64_to_cpu(sbi->s_ftrfs_sb->s_block_count); + buf->f_bfree = sbi->s_free_blocks; + buf->f_bavail = sbi->s_free_blocks; + buf->f_files = le64_to_cpu(sbi->s_ftrfs_sb->s_inode_count); + buf->f_ffree = sbi->s_free_inodes; + buf->f_namelen = FTRFS_MAX_FILENAME; + + return 0; +} + +/* + * put_super — release superblock resources + */ +static void ftrfs_put_super(struct super_block *sb) +{ + struct ftrfs_sb_info *sbi = FTRFS_SB(sb); + + if (sbi) { + ftrfs_destroy_bitmap(sb); + brelse(sbi->s_sbh); + kfree(sbi->s_ftrfs_sb); + kfree(sbi); + sb->s_fs_info = NULL; + } +} + +static const struct super_operations ftrfs_super_ops = { + .alloc_inode = ftrfs_alloc_inode, + .free_inode = ftrfs_free_inode, + .put_super = ftrfs_put_super, + .write_inode = ftrfs_write_inode, + .statfs = ftrfs_statfs, +}; + +/* + * ftrfs_fill_super — read superblock from disk and initialize VFS sb + */ +int ftrfs_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct ftrfs_sb_info *sbi; + struct ftrfs_super_block *fsb; + struct buffer_head *bh; + struct inode *root_inode; + __u32 crc; + int ret = -EINVAL; + + /* Set block size */ + if (!sb_set_blocksize(sb, FTRFS_BLOCK_SIZE)) { + errorf(fc, "ftrfs: unable to set block size %d", FTRFS_BLOCK_SIZE); + return -EINVAL; + } + + /* Read block 0 — superblock */ + bh = sb_bread(sb, 0); + if (!bh) { + errorf(fc, "ftrfs: unable to read superblock"); + return -EIO; + } + + fsb = (struct ftrfs_super_block *)bh->b_data; + + /* Verify magic */ + if (le32_to_cpu(fsb->s_magic) != FTRFS_MAGIC) { + errorf(fc, "ftrfs: bad magic 0x%08x (expected 0x%08x)", + le32_to_cpu(fsb->s_magic), FTRFS_MAGIC); + goto out_brelse; + } + + /* Verify CRC32 of superblock (excluding the crc32 field itself) */ + crc = ftrfs_crc32(fsb, offsetof(struct ftrfs_super_block, s_crc32)); + if (crc != le32_to_cpu(fsb->s_crc32)) { + errorf(fc, "ftrfs: superblock CRC32 mismatch (got 0x%08x, expected 0x%08x)", + crc, le32_to_cpu(fsb->s_crc32)); + goto out_brelse; + } + + /* Allocate in-memory sb info */ + sbi = kzalloc(sizeof(*sbi), GFP_KERNEL); + if (!sbi) { + ret = -ENOMEM; + goto out_brelse; + } + + sbi->s_ftrfs_sb = kzalloc(sizeof(*sbi->s_ftrfs_sb), GFP_KERNEL); + if (!sbi->s_ftrfs_sb) { + ret = -ENOMEM; + goto out_free_sbi; + } + + memcpy(sbi->s_ftrfs_sb, fsb, sizeof(*fsb)); + sbi->s_sbh = bh; + sbi->s_free_blocks = le64_to_cpu(fsb->s_free_blocks); + sbi->s_free_inodes = le64_to_cpu(fsb->s_free_inodes); + spin_lock_init(&sbi->s_lock); + + sb->s_fs_info = sbi; + sb->s_magic = FTRFS_MAGIC; + sb->s_op = &ftrfs_super_ops; + sb->s_maxbytes = MAX_LFS_FILESIZE; + + /* Read root inode (inode 1) */ + root_inode = ftrfs_iget(sb, 1); + if (IS_ERR(root_inode)) { + ret = PTR_ERR(root_inode); + pr_err("ftrfs: failed to read root inode: %d\n", ret); + goto out_free_fsb; + } + + sb->s_root = d_make_root(root_inode); + if (!sb->s_root) { + ret = -ENOMEM; + goto out_free_fsb; + } + + if (ftrfs_setup_bitmap(sb)) { + ret = -ENOMEM; + goto out_free_fsb; + } + + pr_info("ftrfs: mounted (blocks=%llu free=%lu inodes=%llu)\n", + le64_to_cpu(fsb->s_block_count), + sbi->s_free_blocks, + le64_to_cpu(fsb->s_inode_count)); + + return 0; + +out_free_fsb: + kfree(sbi->s_ftrfs_sb); +out_free_sbi: + kfree(sbi); + sb->s_fs_info = NULL; +out_brelse: + brelse(bh); + return ret; +} + +/* + * fs_context ops — kernel 5.15+ mount API + */ +static int ftrfs_get_tree(struct fs_context *fc) +{ + return get_tree_bdev(fc, ftrfs_fill_super); +} + +static const struct fs_context_operations ftrfs_context_ops = { + .get_tree = ftrfs_get_tree, +}; + +static int ftrfs_init_fs_context(struct fs_context *fc) +{ + fc->ops = &ftrfs_context_ops; + return 0; +} + +static struct file_system_type ftrfs_fs_type = { + .owner = THIS_MODULE, + .name = "ftrfs", + .init_fs_context = ftrfs_init_fs_context, + .kill_sb = kill_block_super, + .fs_flags = FS_REQUIRES_DEV, +}; + +/* + * Inode cache constructor + */ +static void ftrfs_inode_init_once(void *obj) +{ + struct ftrfs_inode_info *fi = obj; + + inode_init_once(&fi->vfs_inode); +} + +/* + * Module init / exit + */ +static int __init ftrfs_init(void) +{ + int ret; + + ftrfs_inode_cachep = kmem_cache_create( + "ftrfs_inode_cache", + sizeof(struct ftrfs_inode_info), + 0, + SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT, + ftrfs_inode_init_once); + + if (!ftrfs_inode_cachep) { + pr_err("ftrfs: failed to create inode cache\n"); + return -ENOMEM; + } + + ret = register_filesystem(&ftrfs_fs_type); + if (ret) { + pr_err("ftrfs: failed to register filesystem: %d\n", ret); + kmem_cache_destroy(ftrfs_inode_cachep); + return ret; + } + + pr_info("ftrfs: module loaded (FTRFS Fault-Tolerant Radiation-Robust FS)\n"); + return 0; +} + +static void __exit ftrfs_exit(void) +{ + unregister_filesystem(&ftrfs_fs_type); + rcu_barrier(); + kmem_cache_destroy(ftrfs_inode_cachep); + pr_info("ftrfs: module unloaded\n"); +} + +module_init(ftrfs_init); +module_exit(ftrfs_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("roastercode - Aurelien DESBRIERES "); +MODULE_DESCRIPTION("FTRFS: Fault-Tolerant Radiation-Robust Filesystem"); +MODULE_VERSION("0.1.0"); +MODULE_ALIAS_FS("ftrfs"); -- 2.52.0